What is your ACTUAL reasoning for undercutting?

[Rockazoid]

Nine hundred million times this.

People undercutting massively out of spite just end up hurting their own margins. I'll undercut by 1 Gil every day for 2-3 months if necessary until it gets bought, and if they try to remove/put the price back up to where everyone else is, I'll just bump up my price again to undercut the cheapest price by 1 Gil.

I often cut by about 10% under 100k. Just because it's faster. Sometimes I'll even buy the cheapest one if it's massively cheaper, that way. They get their gil. And now I can get mine. But idc personally. I'm not a market king or a Crafter or gatherer. So I fatten the economy PLENTY by buying stuff with my own gil.